Ebeam align on the fly

ABSTRACT

Lithographic apparatuses suitable for, and methodologies involving, complementary e-beam lithography (CEBL) are described. In an example, a method of real-time alignment of a wafer situated on a stage of an e-beam tool involves collecting backscattered electrons from an underlying patterned feature of the wafer while an e-beam column of the e-beam tool writes during scanning of the stage. The collecting is performed by an electron detector placed at the e-beam column bottom. The method also involves performing linear corrections of an alignment of the stage relative to the e-beam column based on the collecting.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/012,209, filed on Jun. 13, 2014, the entire contents of which arehereby incorporated by reference herein.

TECHNICAL FIELD

Embodiments of the invention are in the field of lithography and, inparticular, lithography involving complementary e-beam lithography(CEBL).

BACKGROUND

For the past several decades, the scaling of features in integratedcircuits has been a driving force behind an ever-growing semiconductorindustry. Scaling to smaller and smaller features enables increaseddensities of functional units on the limited real estate ofsemiconductor chips.

Integrated circuits commonly include electrically conductivemicroelectronic structures, which are known in the art as vias. Vias canbe used to electrically connect metal lines above the vias to metallines below the vias. Vias are typically formed by a lithographicprocess. Representatively, a photoresist layer may be spin coated abovea dielectric layer, the photoresist layer may be exposed to patternedactinic radiation through a patterned mask, and then the exposed layermay be developed in order to form an opening in the photoresist layer.Next, an opening for the via may be etched in the dielectric layer byusing the opening in the photoresist layer as an etch mask. This openingis referred to as a via opening. Finally, the via opening may be filledwith one or more metals or other conductive materials to form the via.

In the past, the sizes and the spacing of vias has progressivelydecreased, and it is expected that in the future the sizes and thespacing of the vias will continue to progressively decrease, for atleast some types of integrated circuits (e.g., advanced microprocessors,chipset components, graphics chips, etc.). One measure of the size ofthe vias is the critical dimension of the via opening. One measure ofthe spacing of the vias is the via pitch. Via pitch represents thecenter-to-center distance between the closest adjacent vias. Whenpatterning extremely small vias with extremely small pitches by suchlithographic processes, several challenges present themselves.

One such challenge is that the overlay between the vias and theoverlying metal lines, and the overlay between the vias and theunderlying metal lines, generally needs to be controlled to hightolerances on the order of a quarter of the via pitch. As via pitchesscale ever smaller over time, the overlay tolerances tend to scale withthem at an even greater rate than lithographic equipment is able toscale with.

Another such challenge is that the critical dimensions of the viaopenings generally tend to scale faster than the resolution capabilitiesof lithographic scanners. Shrink technologies exist to shrink thecritical dimensions of the via openings. However, the shrink amounttends to be limited by the minimum via pitch, as well as by the abilityof the shrink process to be sufficiently optical proximity correction(OPC) neutral, and to not significantly compromise line width roughness(LWR) and/or critical dimension uniformity (CDU).

Yet another such challenge is that the LWR and/or CDU characteristics ofphotoresists generally need to improve as the critical dimensions of thevia openings decrease in order to maintain the same overall fraction ofthe critical dimension budget. However, currently the LWR and/or CDUcharacteristics of most photoresists are not improving as rapidly as thecritical dimensions of the via openings are decreasing. A further suchchallenge is that the extremely small via pitches generally tend to bebelow the resolution capabilities of even extreme ultraviolet (EUV)lithographic scanners. As a result, commonly two, three, or moredifferent lithographic masks may have to be used, which tends toincrease the fabrication costs. At some point, if pitches continue todecrease, it may not be possible, even with multiple masks, to print viaopenings for these extremely small pitches using conventional scanners.

In the same vein, the fabrication of cuts (i.e., disruptions) in themetal line structures associated with metal vias is faced with similarscaling issues.

Thus, improvements are needed in the area of lithographic processingtechnologies and capabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a cross-sectional view of a starting structurefollowing deposition, but prior to patterning, of a hardmask materiallayer formed on an interlayer dielectric (ILD) layer.

FIG. 1B illustrates a cross-sectional view of the structure of FIG. 1Afollowing patterning of the hardmask layer by pitch halving.

FIG. 2 illustrates cross-sectional views in aspacer-based-sextuple-patterning (SBSP) processing scheme which involvespitch division by a factor of six.

FIG. 3 illustrates cross-sectional views in aspacer-based-nonuple-patterning (SBNP) processing scheme which involvespitch division by a factor of nine.

FIG. 4 is a cross-sectional schematic representation of an ebeam columnof an electron beam lithography apparatus.

FIG. 5 is a schematic demonstrating an optical scanner overlay limitedby its ability to model in plane grid distortions (IPGD).

FIG. 6 is a schematic demonstrating distorted grid information using analign on the fly approach, in accordance with an embodiment of thepresent invention.

FIG. 7 provides a sample calculation showing the information to betransferred to pattern a general/conventional layout at 50% density on a300 mm wafer in contrast to a via pattern at 5% density, in accordancewith an embodiment of the present invention.

FIG. 8 illustrates a gridded layout approach for simplified design rulelocations for vias, and cut start/stop, in accordance with an embodimentof the present invention.

FIG. 9 illustrates the allowable placement of cuts, in accordance withan embodiment of the present invention.

FIG. 10 illustrates a via layout among lines A and B, in accordance withan embodiment of the present invention.

FIG. 11 illustrates a cut layout among lines A-E, in accordance with anembodiment of the present invention.

FIG. 12 illustrates a wafer having a plurality of die locations thereonand an overlying dashed box representing a wafer field of a singlecolumn, in accordance with an embodiment of the present invention.

FIG. 13 illustrates a wafer having a plurality of die locations thereonand an overlying actual target wafer field of a single column andincreased peripheral area for on the fly correction, in accordance withan embodiment of the present invention.

FIG. 14 demonstrates the effect of a few degree wafer rotation on thearea to be printed (inner dark, thin dashed) against the original targetarea (inner light, thick dashed), in accordance with an embodiment ofthe present invention.

FIG. 15 illustrates a plan view of horizontal metal lines as representedoverlaying vertical metal lines in the previous metallization layer, inaccordance with an embodiment of the present invention.

FIG. 16 illustrates a plan view of horizontal metal lines as representedoverlaying vertical metal lines in the previous metallization layer,where metal lines of differing width/pitch overlap in a verticaldirection, in accordance with an embodiment of the present invention.

FIG. 17 illustrates a plan view of conventional metal lines asrepresented overlaying vertical metal lines in the previousmetallization layer.

FIG. 18 illustrates an aperture (left) of a BAA relative to a line(right) to be cut or to have vias placed in targeted locations while theline is scanned under the aperture.

FIG. 19 illustrates two non-staggered apertures (left) of a BAA relativeto two lines (right) to be cut or to have vias placed in targetedlocations while the lines are scanned under the apertures.

FIG. 20 illustrates two columns of staggered apertures (left) of a BAArelative to a plurality of lines (right) to be cut or to have viasplaced in targeted locations while the lines are scanned under theapertures, with scanning direction shown by the arrow, in accordancewith an embodiment of the present invention.

FIG. 21A illustrates two columns of staggered apertures (left) of a BAArelative to a plurality of lines (right) having cuts (breaks in thehorizontal lines) or vias (filled-in boxes) patterned using thestaggered BAA, with scanning direction shown by the arrow, in accordancewith an embodiment of the present invention.

FIG. 21B illustrates a cross-sectional view of a stack of metallizationlayers in an integrated circuit based on metal line layouts of the typeillustrated in FIG. 21A, in accordance with an embodiment of the presentinvention.

FIG. 22 illustrates apertures of a BAA having a layout of threedifferent staggered arrays, in accordance with an embodiment of thepresent invention.

FIG. 23 illustrates apertures of a BAA having a layout of threedifferent staggered arrays, where the ebeam covers only one of thearrays, in accordance with an embodiment of the present invention.

FIG. 24A includes a cross-sectional schematic representation of an ebeamcolumn of an electron beam lithography apparatus having a deflector toshift the beam, in accordance with an embodiment of the presentinvention.

FIG. 24B illustrates a three (or up to n) pitch array for a BAA 2450having pitch #1, cut #1, a pitch #2, cut #2 and a pitch # N, cut # N, inaccordance with an embodiment of the present invention.

FIG. 24C illustrates a zoom in slit for inclusion on an ebeam column, inaccordance with an embodiment of the present invention.

FIG. 25 illustrates apertures of a BAA having a layout of threedifferent pitch staggered arrays, where the ebeam covers all of thearrays, in accordance with an embodiment of the present invention.

FIG. 26 illustrates a three beam staggered aperture array (left) of aBAA relative to a plurality of large lines (right) having cuts (breaksin the horizontal lines) or vias (filled-in boxes) patterned using theBAA, with scanning direction shown by the arrow, in accordance with anembodiment of the present invention.

FIG. 27 illustrates a three beam staggered aperture array (left) of aBAA relative to a plurality of medium sized lines (right) having cuts(breaks in the horizontal lines) or vias (filled-in boxes) patternedusing the BAA, with scanning direction shown by the arrow, in accordancewith an embodiment of the present invention.

FIG. 28 illustrates a three beam staggered aperture array (left) of aBAA relative to a plurality of small lines (right) having cuts (breaksin the horizontal lines) or vias (filled-in boxes) patterned using theBAA, with scanning direction shown by the arrow, in accordance with anembodiment of the present invention.

FIG. 29A illustrates a three beam staggered aperture array (left) of aBAA relative to a plurality of lines of varying size (right) having cuts(breaks in the horizontal lines) or vias (filled-in boxes) patternedusing the BAA, with scanning direction shown by the arrow, in accordancewith an embodiment of the present invention.

FIG. 29B illustrates a cross-sectional view of a stack of metallizationlayers in an integrated circuit based on metal line layouts of the typeillustrated in FIG. 29A, in accordance with an embodiment of the presentinvention.

FIG. 30 illustrates a three beam staggered aperture array (left) of aBAA relative to a plurality of lines of varying size (right) having cuts(breaks in the horizontal lines) or vias (filled-in boxes) patternedusing the BAA, with scanning direction shown by the arrow, in accordancewith an embodiment of the present invention.

FIG. 31 illustrates three sets of lines of differing pitch withoverlying corresponding apertures on each line, in accordance with anembodiment of the present invention.

FIG. 32 illustrates a plurality of different sized lines (right)including one very large line, and a beam aperture arrays vertical pitchlayout (three arrays) on a common grid, in accordance with an embodimentof the present invention.

FIG. 33 illustrates a plurality of different sized lines (right), and auniversal cutter pitch array (left), in accordance with an embodiment ofthe present invention.

FIG. 34 demonstrates the 2*EPE rule for a universal cutter (left) asreferenced against two lines (right), in accordance with an embodimentof the present invention.

FIG. 35 illustrates a plan view and corresponding cross-sectional viewof a previous layer metallization structure, in accordance with anembodiment of the present invention.

FIG. 36A illustrates a cross-sectional view of a non-planarsemiconductor device having fins, in accordance with an embodiment ofthe present invention.

FIG. 36B illustrates a plan view taken along the a-a′ axis of thesemiconductor device of FIG. 36A, in accordance with an embodiment ofthe present invention.

FIG. 37 illustrates a computing device in accordance with oneimplementation of the invention.

FIG. 38 illustrates a block diagram of an exemplary computer system, inaccordance with an embodiment of the present invention.

FIG. 39 is an interposer implementing one or more embodiments of theinvention.

FIG. 40 is a computing device built in accordance with an embodiment ofthe invention.

DESCRIPTION OF THE EMBODIMENTS

Lithographic apparatuses suitable for, and methodologies involving,complementary e-beam lithography (CEBL) are described. In the followingdescription, numerous specific details are set forth, such as specifictooling, integration and material regimes, in order to provide athorough understanding of embodiments of the present invention. It willbe apparent to one skilled in the art that embodiments of the presentinvention may be practiced without these specific details. In otherinstances, well-known features, such as single or dual damasceneprocessing, are not described in detail in order to not unnecessarilyobscure embodiments of the present invention. Furthermore, it is to beunderstood that the various embodiments shown in the Figures areillustrative representations and are not necessarily drawn to scale. Insome cases, various operations will be described as multiple discreteoperations, in turn, in a manner that is most helpful in understandingthe present invention, however, the order of description should not beconstrued to imply that these operations are necessarily orderdependent. In particular, these operations need not be performed in theorder of presentation.

One or more embodiments described herein are directed to lithographicapproaches and tooling involving or suitable for complementary e-beamlithography (CEBL), including semiconductor processing considerationswhen implementing such approaches and tooling.

Complementary lithography draws on the strengths of two lithographytechnologies, working hand-in-hand, to lower the cost of patterningcritical layers in logic devices at 20 nm half-pitch and below, inhigh-volume manufacturing (HVM). The most cost-effective way toimplement complementary lithography is to combine optical lithographywith e-beam lithography (EBL). The process of transferring integratedcircuit (IC) designs to the wafer entails the following: opticallithography to print unidirectional lines (either strictlyunidirectional or predominantly unidirectional) in a pre-defined pitch,pitch division techniques to increase line density, and EBL to “cut” thelines. EBL is also used to pattern other critical layers, notablycontact and via holes. Optical lithography can be used alone to patternother layers. When used to complement optical lithography, EBL isreferred to as CEBL, or complementary EBL. CEBL is directed to cuttinglines and holes. By not attempting to pattern all layers, CEBL plays acomplementary but crucial role in meeting the industry's patterningneeds at advanced (smaller) technology nodes (e.g., 10 nm or smallersuch as 7 nm or 5 nm technology nodes). CEBL also extends the use ofcurrent optical lithography technology, tools and infrastructure.

As mentioned above, pitch division techniques can be used to increase aline density prior to using EBL to cut such lines. In a first example,pitch halving can be implemented to double the line density of afabricated grating structure. FIG. 1A illustrates a cross-sectional viewof a starting structure following deposition, but prior to patterning,of a hardmask material layer formed on an interlayer dielectric (ILD)layer. FIG. 1B illustrates a cross-sectional view of the structure ofFIG. 1A following patterning of the hardmask layer by pitch halving.

Referring to FIG. 1A, a starting structure 100 has a hardmask materiallayer 104 formed on an interlayer dielectric (ILD) layer 102. Apatterned mask 106 is disposed above the hardmask material layer 104.The patterned mask 106 has spacers 108 formed along sidewalls offeatures (lines) thereof, on the hardmask material layer 104.

Referring to FIG. 1B, the hardmask material layer 104 is patterned in apitch halving approach. Specifically, the patterned mask 106 is firstremoved. The resulting pattern of the spacers 108 has double thedensity, or half the pitch or the features of the mask 106. The patternof the spacers 108 is transferred, e.g., by an etch process, to thehardmask material layer 104 to form a patterned hardmask 110, as isdepicted in FIG. 1B. In one such embodiment, the patterned hardmask 110is formed with a grating pattern having unidirectional lines. Thegrating pattern of the patterned hardmask 110 may be a tight pitchgrating structure. For example, the tight pitch may not be achievabledirectly through conventional lithography techniques. Even further,although not shown, the original pitch may be quartered by a secondround of spacer mask patterning. Accordingly, the grating-like patternof the patterned hardmask 110 of FIG. 1B may have hardmask lines spacedat a constant pitch and having a constant width relative to one another.The dimensions achieved may be far smaller than the critical dimensionof the lithographic technique employed.

Accordingly, as a first portion of a CEBL integration scheme, a blanketfilm may be patterned using lithography and etch processing which mayinvolve, e.g., spacer-based-double-patterning (SBDP) or pitch halving,or spacer-based-quadruple-patterning (SBQP) or pitch quartering. It isto be appreciated that other pitch division approaches may also beimplemented.

For example, FIG. 2 illustrates cross-sectional views in aspacer-based-sextuple-patterning (SBSP) processing scheme which involvespitch division by a factor of six. Referring to FIG. 2, at operation(a), a sacrificial pattern X is shown following litho, slim and etchprocessing. At operation (b), spacers A and B are shown followingdeposition and etching. At operation (c), the pattern of operation (b)is shown following spacer A removal. At operation (d), the pattern ofoperation (c) is shown following spacer C deposition. At operation (e),the pattern of operation (d) is shown following spacer C etch. Atoperation (f), a pitch/6 pattern is achieved following sacrificialpattern X removal and spacer B removal.

In another example, FIG. 3 illustrates cross-sectional views in aspacer-based-nonuple-patterning (SBNP) processing scheme which involvespitch division by a factor of nine. Referring to FIG. 3, at operation(a), a sacrificial pattern X is shown following litho, slim and etchprocessing. At operation (b), spacers A and B are shown followingdeposition and etching. At operation (c), the pattern of operation (b)is shown following spacer A removal. At operation (d), the pattern ofoperation (c) is shown following spacer C and D deposition and etch. Atoperation (e), a pitch/9 pattern is achieved following spacer C removal.

In any case, in an embodiment, complementary lithography as describedherein involves first fabricating a gridded layout by conventional orstate-of the-art lithography, such as 193 nm immersion lithography(193i). Pitch division may be implemented to increase the density oflines in the gridded layout by a factor of n. Gridded layout formationwith 193i lithography plus pitch division by a factor of n can bedesignated as 193i+P/n Pitch Division. Patterning of the pitch dividedgridded layout may then be patterned using electron beam direct write(EBDW) “cuts,” as is described in greater detail below. In one suchembodiment, 193 nm immersion scaling can be extended for manygenerations with cost effective pitch division. Complementary EBL isused to break gratings continuity and to pattern vias.

More specifically, embodiments described herein are directed topatterning features during the fabrication of an integrated circuit. Inone embodiment, CEBL is used to pattern openings for forming vias. Viasare metal structures used to electrically connect metal lines above thevias to metal lines below the vias. In another embodiment, CEBL is usedto form non-conductive spaces or interruptions along the metal lines.Conventionally, such interruptions have been referred to as “cuts” sincethe process involved removal or cutting away of portions of the metallines. However, in a damascene approach, the interruptions may bereferred to as “plugs” which are regions along a metal line trajectorythat are actually not metal at any stage of the fabrication scheme, butare rather preserved regions where metal cannot be formed. In eithercase, however, use of the terms cuts or plugs may be done sointerchangeably. Via opening and metal line cut or plug formation iscommonly referred to as back end of line (BEOL) processing for anintegrated circuit. In another embodiment, CEBL is used for front end ofline (FEOL) processing. For example, the scaling of active regiondimensions (such as fin dimensions) and/or associated gate structurescan be performed using CEBL techniques as described herein.

As described above, electron beam (ebeam) lithography may be implementedto complement standard lithographic techniques in order to achieveddesired scaling of features for integrated circuit fabrication. Anelectron beam lithography tool may be used to perform the ebeamlithography. In an exemplary embodiment, FIG. 4 is a cross-sectionalschematic representation of an ebeam column of an electron beamlithography apparatus.

Referring to FIG. 4, an ebeam column 400 includes an electron source 402for providing a beam of electrons 404. The beam of electrons 404 ispassed through a limiting aperture 406 and, subsequently, through highaspect ratio illumination optics 408. The outgoing beam 410 is thenpassed through a slit 412 and may be controlled by a slim lens 414,e.g., which may be magnetic. Ultimately, the beam 404 is passed througha shaping aperture 416 (which may be a one-dimensional (1-D) shapingaperture) and then through a blanker aperture array (BAA) 418. The BAA418 includes a plurality of physical apertures therein, such as openingsformed in a thin slice of silicon. It may be the case that only aportion of the BAA 418 is exposed to the ebeam at a given time.Alternatively, or in conjunction, only a portion 420 of the ebeam 404that passes through the BAA 418 is allowed to pass through a finalaperture 422 (e.g., beam portion 421 is shown as blocked) and, possibly,a stage feedback deflector 424.

Referring again to FIG. 4, the resulting ebeam 426 ultimately impingesas a spot 428 on a surface of a wafer 430, such as a silicon wafer usedin IC manufacture. Specifically, the resulting ebeam may impinge on aphoto-resist layer on the wafer, but embodiments are not so limited. Astage scan 432 moves the wafer 430 relative to the beam 426 along thedirection of the arrow 434 shown in FIG. 4. It is to be appreciated thatan ebeam tool in its entirely may include numerous columns 400 of thetype depicted in FIG. 4. Also, as described in some embodiments below,the ebeam tool may have an associated base computer, and each column mayfurther have a corresponding column computer.

One drawback of state-of-the-art e-beam lithography is that it is notreadily adoptable into a high volume manufacturing (HVM) environment foradvanced integrated circuit manufacturing. Today's e-beam tooling andassociated methodology has proven to be too slow with respect tothroughput requirements for HVM wafer processing. Embodiments describedherein are directed to enabling the use of EBL in an HVM environment. Inparticular, many embodiments described herein enable improved throughputin an EBL tool to allow for the use of EBL in an HVM environment.

Described below are seven different aspects of embodiments that canimprove EBL beyond its current capabilities. It is to be appreciatedthat, although broken out as seven distinct aspects of embodiments,embodiments described below may be used independently or in any suitablecombination to achieve improvements in EBL throughput for an HVMenvironment. As described in greater detail below, in a first aspect,alignment considerations for a wafer subjected to ebeam patterning on anebeam tool are addressed. In a second aspect, data compression or datareduction for ebeam tool simplification is described. In a third aspect,the implementation of regions of uniform metal or other grating patterndensity for an integrated circuit layout is described. In a fourthaspect, a staggered blanker aperture array (BAA) for an ebeam tool isdescribed. In a fifth aspect, a three beam aperture array for an ebeamtool is described. In a sixth aspect, a non-universal cutter for anebeam tool is described. In a seventh aspect, a universal cutter for anebeam tool is described.

For all aspects, in an embodiment, when referring below to openings orapertures in a blanker aperture array (BAA), all or some of the openingsor apertures of the BAA can be switched open or “closed” (e.g., by beamdeflecting) as the wafer/die moves underneath along a wafer travel orscan direction. In one embodiment, the BAA can be independentlycontrolled as to whether each opening passes the ebeam through to thesample or deflects the beam into, e.g., a Faraday cup or blankingaperture. The ebeam column or apparatus including such a BAA may bebuilt to deflect the overall beam coverage to just a portion of the BAA,and then individual openings in the BAA are electrically configured topass the ebeam (“on”) or not pass (“off”). For example, un-deflectedelectrons pass through to the wafer and expose a resist layer, whiledeflected electrons are caught in the Faraday cup or blanking aperture.It is to be appreciated that reference to “openings” or “openingheights” refers to the spot size impinged on the receiving wafer and notto the physical opening in the BAA since the physical openings aresubstantially larger (e.g., micron scale) than the spot size (e.g.,nanometer scale) ultimately generated from the BAA. Thus, when describedherein as the pitch of a BAA or column of openings in a BAA being saidto “correspond” to the pitch of metal lines, such description actuallyrefers to the relationship between pitch of the impinging spots asgenerated from the BAA and the pitch of the lines being cut. As anexample provided below, the spots generated from the BAA 2110 have apitch the same as the pitch of the lines 2100 (when both columns of BAAopenings are considered together). Meanwhile, the spots generated fromonly one column of the staggered array of the BAA 2110 have twice thepitch as the pitch of the lines 2100.

For all aspects, it is also to be appreciated that, in some embodiments,an ebeam column as described above may also include other features inaddition to those described in association with FIG. 4. For example, inan embodiment, the sample stage can be rotated by 90 degrees toaccommodate alternating metallization layers which may be printedorthogonally to one another (e.g., rotated between X and Y scanningdirections). In another embodiment, an e-beam tool is capable ofrotating a wafer by 90 degrees prior to loading the wafer on the stage.Other additional embodiments are described below in association withFIGS. 24A-24C.

In a first aspect of embodiments of the present invention, alignmentconsiderations for a wafer subjected to ebeam patterning on an ebeamtool are addressed.

Approaches described below may be implemented to overcome excessivecontribution to edge placement error (EPE) from layer to layer physicaloverlay when a layer is patterned by an imaging tool (e.g., an opticalscanner). In an embodiment, the approaches described below areapplicable for an imaging tool that otherwise uses preselected samplingof wafer coordinate system markers (i.e., alignment marks) to estimatewafer processing induced in-plane grid distortion parameters on aprocessed wafer. The collected alignment information (e.g., sampledwafer in plane grid distortion) is typically fit to a predefined orderpolynomial. The fit is then typically used as a representation of adistorted grid to adjust various scanner printing parameters and toachieve the best possible overlay between underlying and printed layers.

Instead, in an embodiment, use of an ebeam for patterning allows forcollection of alignment information during a write at any point on thepattern (“align on the fly”) containing underlying layer features, andnot only on every die. For example, an electron detector is placed atthe ebeam column bottom in order to collect backscattered electrons fromalignment marks or other underlying patterned feature. A straightforward linear model allows for collection of such information hundredsof time within every die as an ebeam column writes (and the detectordetects) while the stage is scanning underneath the column during dieexposure. In one such embodiment, there is no need for fittingpolynomial and estimating complex correction parameters of higherorders. Rather, only simple linear corrections can be used.

In an embodiment, in practice, multiple (hundreds) time positions of theebeam can and will be registered against alignment marks patterned on aprevious layer in scribe lines as well as inside active areas of thedies. The registering may be performed using drop in cells usuallypresent for the purpose of characterizing patterning characteristics ofa layer pattern to be exposed without loss of tool throughput of COO(cost of ownership).

In the case that on-the-fly alignment is not implemented, thealternative is to use higher order polynomials, as described above.However, alignment based on higher order polynomials is used to fitrelatively sparse alignment information (e.g., only 10-15% of dieslocations to be patterned are used to collect in-plane grid distortionson the wafer), whereas un-modeled (residual) fit errors constitute about50% of maximum total overlay predicted errors. Collecting much moredense alignment information and using even higher order polynomial forfit and patterning correction might improve overlay somewhat yet thiswill be achieved at significant throughput and cost of ownership loss.

To provide context, wafer processing induced in-plane grid distortionoccurs from multiple sources, including but not limited tobackscatter/field displacement errors due to metal/other layersunderneath the pattern being printed, wafer bowing/localized incrementalwafer expansion due to pattern writing heat effects, and otheradditional effects that contribute greatly to EPE. If corrections arenot made, the likelihood of patterning a wafer with localized grosspatterning misalignment is very high.

FIG. 5 is a schematic demonstrating an optical scanner overlay limitedby its ability to model in plane grid distortions (IPGD). Referring tothe left-hand portion 502 of FIG. 5, a die grid 504 on a wafer 506 isdistorted by wafer processing. Vectors indicate corners displacement ofevery die versus the initial positioning (e.g., first layer print).Referring to the right-hand portion 510 of FIG. 5, a conventionalstepper will collect relatively sparse distorted grid information onthis layer, as represented by the dots 512. Accordingly, using higherorder polynomials allows fitting of relatively sparse alignmentinformation. The number of locations is optimized for “acceptable”residuals after the model fits to grid representation obtained from gridcoordinate information in the sampled locations. Overhead time is neededto collect this information.

In contrast to the relatively sparse distorted grid informationcollected as represented in FIG. 5, FIG. 6 is a schematic demonstratingdistorted grid information using an align on the fly approach, inaccordance with an embodiment of the present invention. Referring toFIG. 6, as an ebeam writes every die, the detector at the column bottomcollects information about positional coordinated of an underlyinglayer. Necessary adjustment to writing position can be performed throughstage position control in real time everywhere on the wafer at no orminimal overhead time increase or throughput loss. In particular, FIG. 6illustrates the same plot 602 as provided in FIG. 5. A zoomed-inexemplary die region 604 illustrates the scanning directions 606 withinthe die region 604.

In a second aspect of embodiments of the present invention, datacompression or data reduction for ebeam tool simplification isdescribed.

Approaches described herein involve restricting data to allow massivecompression of data, reducing a data path and ultimately providing for amuch simpler ebeam writing tool. More particularly, embodimentsdescribed enable significant reduction in the amount of data that mustbe passed to an ebeam column of an ebeam tool. A practical approach isprovided for allowing a sufficient amount of data to write the columnfield and adjust the column field for field edge placement error, whilekeeping within the electrical bandwidth limits of the physical hardware.Without implementing such embodiments, the required bandwidth isapproximately 100 times that possible by today's electronics. In anembodiment, data reduction or compression approaches described hereincan be implemented to substantially increase throughput capabilities ofan EBL tool. By increasing the throughput capabilities, EBL can morereadily be adopted in an HVM environment, such as into an integratedcircuit manufacturing environment.

FIG. 7 provides a sample calculation showing the information to betransferred to pattern a general/conventional layout at 50% density on a300 mm wafer in contrast to a via pattern at 5% density, in accordancewith an embodiment of the present invention. Referring to FIG. 7,information to be transferred is according to equation (A). Informationtransfer is according to equation (B) with information loss due to edgeplacement error (EPE) uncertainty (Ap) is minimal resolved feature, andAPV is equal to 2EPE. Assuming EBDW tool resolution of AP is equal to 10nm and EPE is equal to 2.5 nm, the information volume to be transferredby such a general purpose imaging system in 1 m² (assuming 50% patterndensity) will be according to equation (C). A 300 mm wafer area is 706cm² which is 0.0706 m². Correspondingly, to pattern a general layout at50% density on a 300 mm wafer, the number of bytes needed to betransferred is according to equation (D). The result is 70 TB to betransferred in 6 minutes assuming 10 wph TPT for a transfer rate of194.4 GB/s. In accordance with an embodiment of the present invention,an EBDW tool that is designed to print vias (and/or cuts) at a patterndensity of approximately 10% will require correspondingly smallerinformation to be transferred, e.g., at a realistic 40 GB/s transferrate. In a specific embodiment, an EBDW tool is designed to print vias(and/or cuts) at a pattern density of approximately 5% and requirescorrespondingly smaller information to be transferred, e.g., 7 TB at arealistic 20 GB/s transfer rate.

With reference again to FIG. 7, the information transfer is reduced to arelative (integerized) distance instead of transferring absolute 64 bitcoordinates. By using an ebeam tool to pattern only vias at less thanapproximately 10% density, and even as low as 5% density, versus ageneral layout pattern at 50% density, for example, a reduction in theamount of data transfer from 70+TB in 6 minutes to less than 7 TB in 6minutes can be realized, allowing the ebeam apparatus to achieve themanufacturing throughput needed for high volume production.

In an embodiment, one or more of the following four approaches isimplemented for data reduction: (1) all design rules for vias and cutsare simplified to reduce the number of positions that a via can occupy,and where the start and stop of a line cut is possibly located; (2)encryption of placement of cut starts and stops, as well as distancesbetween vias, is encrypted as n*min distance (this removes the need tosend 64 bit address for each start and stop location for a cut, as wellas for via locations); (3) for each column in the tool, only the datarequired to make the cuts and vias that fall within this section of thewafer are forwarded to the column computer (each column receives onlythe data needed, in a form encrypted as in part 2); and/or (4) for eachcolumn in the tool, the area that is transmitted is increased by n linesat top, bottom and additional breadth in x is also allowed (accordingly,the associated column computer can adjust on the fly for changes inwafer temperature and alignment without having the entire wafer datatransmitted). In an embodiment, implementation of one or more such datareduction approaches enables simplification of an ebeam tool at least tosome extent. For example, a dedicated computer or processor normallyassociated with a single dedicated column in a multi-column ebeam toolmay be simplified or even altogether eliminated. That is, a singlecolumn equipped with on-board dedicated logic capability may besimplified to move the logic capability off-board or to reduce to amountof on-board logic capability required for each individual column of theebeam tool.

With respect to approach (1) above, FIG. 8 illustrates a gridded layoutapproach for simplified design rule locations for vias, and cutstart/stop, in accordance with an embodiment of the present invention. Ahorizontal grid 800 includes a regular arrangement of line positions,with solid lines 802 representing actual lines and dashed lines 804representing unoccupied line positions. The key to this technique isthat vias (filled-in boxes 806) are on a regular grid (shown as thevertical grid 808 in FIG. 8) and are printed in the scan direction 810parallel with the metal lines (horizontal rectangles with solid outline)that are below the vias. The requirement for this design system is thatvia locations 806 are formed only in alignment with the vertical grid808.

With respect to cuts, cuts are made with a grid that is finer than thevia grid. FIG. 9 illustrates the allowable placement of cuts, inaccordance with an embodiment of the present invention. Referring toFIG. 9, an array of lines 902 has vias 904 positioned therein accordingto grid 906. The allowable placement of cuts (e.g., labeled cuts 908,910 and 912) is indicated by the vertical dashed lines 914, with the vialocations continuing as vertical solid lines 906. The cuts always start,and stop, exactly on the grid 914, which is key to reducing the amountof data transferred from the base computer down to the column computer.It is to be appreciated, however, that the position of the dashedvertical lines 914 appears to be a regular grid, but that is not arequirement. Instead, the pair of lines centered around the via cutlines is the known distance of −xn and +xn relative to the via location.The via locations are a regular grid that is spaced every m units alongthe cut direction.

With respect to approach (2) above, distance-based encryption of cutsand vias may be used to eliminate the need to send 64 bit fulladdresses. For example, rather than sending absolute 64 bit (or 128 bit)addresses for x, and y positions, the distance along the direction oftravel from the left edge (for wafer lines printing in direction movingto right) or from the right edge (for wafer lines printing in thedirection moving to the left) is encrypted. The pair of lines centeredaround the via lines is the known distance of −xn and +xn relative tothe via location, and the via locations are a regular grid that isspaced every m units along the cut direction. Any via print location canthus be encrypted as a distance from zero to the numbered via location(spaced m units apart). This significantly reduces the amount ofpositioning data that must be transmitted.

The amount of information can be further reduced by providing themachine with the relative count of vias from the previous via. FIG. 10illustrates a via layout among lines A and B, in accordance with anembodiment of the present invention. Referring to FIG. 10, the two linesas shown can be reduced as follows: line A: via 1002 spacing +1, +4, +1,+2; line B: via 1004 spacing +9. The via 1002/1004 spacing is accordingto grid 1006. It is to be appreciated that additional communicationtheory of assignment of most likely terms could be further performed toreduce the data space. Even so, even ignoring such further reductionyields an excellent improvement using straight forward compression toreduce 4 vias of 64 bits position, to just a handful of bits.

Similarly, the start and stop of cuts can be reduced to eliminate theneed to send 64 bits (or 128 bits) of positional information for eachcut. Like a light switch, starting a cut means the next data point isthe end of cut, and similarly the next location is the start of the nextcut. Since it is known that cuts end +xn in the direction of travel fromvia locations (and similarly start at −xn), depending upon cutstart/stop, the via location can be encoded and the local columncomputer can be instructed reapply the offset from the via location.FIG. 11 illustrates a cut layout among lines A-E, in accordance with anembodiment of the present invention. Referring to FIG. 11, a substantialdecrease over sending absolute 64 (or 128) bit locations results:spacing from previous cut: A: +5 (shown as space 1102), +1; B: x <nocuts> (whatever x is encrypted as—no cuts for distance); C: +1 (thestopping point of the cut at the left), +4 (the start of the large cutaligned vertically with the start of cut 1102) +3 (the end of the largecut); D: +3, +4; E: +3, +2, +1, +4.

With respect to approach (3) above, for each column, the datatransmitted for cuts and vias is restricted to just that required forthe wafer field that falls under the given column. In an example, FIG.12 illustrates a wafer 1200 having a plurality of die locations 1202thereon and an overlying dashed box 1204 representing a wafer field of asingle column, in accordance with an embodiment of the presentinvention. Referring to FIG. 12, the data transmitted to the localcolumn computer is limited to only the lines that occur in the printedregion shown in dotted lines of box 1204.

With respect to approach (4) above, since correction for wafer bow,heating, and chuck misalignment by an angle theta must be done on thefly, the actual region transmitted to the column computer is a few lineslarger top and bottom, as well as additional data to the left and right.FIG. 13 illustrates a wafer 1300 having a plurality of die locations1302 thereon and an overlying actual target wafer field 1304 of a singlecolumn. As shown in FIG. 13, an increased peripheral area 1306 isprovided to account for on the fly correction, in accordance with anembodiment of the present invention. Referring to FIG. 13, while theincreased peripheral area 1306 slightly increases the amount of datatransmitted to the column computer, it also allows the column printingto correct for wafer misalignment resulting from a myriad of issues byallowing the column to print outside its normal region. Such issues mayinclude wafer alignment issues or local heating issues, etc.

FIG. 14 demonstrates the effect of a few degree wafer rotation on thearea to be printed (inner dark, thin dashed box 1402) against theoriginal target area (inner light, thick dashed box 1304) from FIG. 13,in accordance with an embodiment of the present invention. Referring toFIG. 14, the column computer is able to use the additional transmitteddata to make the necessary printing changes without requiring a complexrotational chuck on the machine (which would otherwise limit the speedof the printing).

In a third aspect of embodiments of the present invention, theimplementation of regions of uniform metal or other grating patterndensity for an integrated circuit layout is described.

In an embodiment, in order to improve throughput of an ebeam apparatus,design rules for interconnect layers are simplified to enable a fixedset of pitches that can be used for logic, SRAM, and Analog/IO regionson the die. In one such embodiment, the metal layout further requiresthat the wires be unidirectional with no jogs, orthogonal directionwires, or hooks on the ends, as is currently used to enable via landingsin conventional, non-ebeam lithography processes.

In a particular embodiment, three different wire widths ofunidirectional wire are permitted within each metallization layer. Gapsin the wires are cut precisely, and all to the vias are self-aligned toa maximum allowed size. The latter is an advantage in minimizing viaresistance for extremely fine pitch wiring. The approach describedherein permits an efficient ebeam line cut and via printing with ebeamthat achieves orders of magnitude improvement over existing ebeamsolutions.

FIG. 15 illustrates a plan view of horizontal metal lines 1502 asrepresented overlaying vertical metal lines 1504 in the previousmetallization layer, in accordance with an embodiment of the presentinvention. Referring to FIG. 15, three different pitch/widths 1506, 1508and 1510 of wires are permitted. The different line types may besegregated into chip regions 1512, 1514 and 1516, respectively, asshown. It is to be appreciated that regions are generally larger thanshown, but to draw to scale would make the detail on the wirescomparatively small. Such regions on the same layer may be fabricatedfirst using conventional lithography techniques.

The advances described in embodiments herein permit precise wiretrimming and fully self-aligned vias between layers. It is to beappreciated that trims occur as needed with no trim-trim (plug) rulesrequired as in current litho-based processes. Furthermore, in anembodiment, via-via rules are significantly removed. Vias of the densityand relationship shown would be difficult or impossible to print usingcurrent optical proximity correction (OPC)-enabled lithographycapability. Similarly, the plug/cut rules that would otherwise precludesome of the cuts shown are removed through use of this technique. Assuch, the interconnect/via layers are less limiting to the design ofcircuits.

Referring again to FIG. 15, in the vertical direction, lines ofdifferent pitches and widths are not overlapping, i.e., each region issegregated in a vertical direction. By contrast, FIG. 16 illustrates aplan view of horizontal metal lines 1602 as represented overlayingvertical metal lines 1604 in the previous metallization layer, wheremetal lines of differing width/pitch overlap in a vertical direction, inaccordance with an embodiment of the present invention. For example,lines pair 1606 overlap in the vertical direction, and lines pair 1608overlap in the vertical direction. Referring again to FIG. 16, theregions may be fully overlapping. The wires of all three sizes may beinterdigitated, if enabled by the lines fabrication method, yet cuts andvias continue to be fully enabled by a universal cutter, as describedbelow in association with another aspect of embodiments of the presentinvention.

To provide context, FIG. 17 illustrates a plan view of conventionalmetal lines 1702 as represented overlaying vertical metal lines in theprevious metallization layer. Referring to FIG. 17, in contrast to thelayouts of FIGS. 15 and 16, bi-directional wires are usedconventionally. Such wiring adds orthogonal wiring in the form of longorthogonal wires, short jogs between tracks to change lanes, and “hooks”at the ends of wires to place a via such that line pullback does notencroach the vias. Examples of such constructs are shown at the Xpositions in FIG. 17. It could be argued that allowance of suchorthogonal constructs provides some small density advantage(particularly the track jog at the upper X), but these significantly adddesign rule complexity/design rule checking as well as preclude a toolsuch as the ebeam methodology from achieving needed throughput.Referring again to FIG. 17, it is to be appreciated that conventionalOPC/lithography would preclude some of the vias shown on the left handside from actually being fabricated.

In a fourth aspect of embodiments of the present invention, a staggeredblanker aperture array (BAA) for an ebeam tool is described.

In an embodiment, a staggered beam aperture array is implemented tosolve throughput of an ebeam machine while also enabling minimum wirepitch. With no stagger, consideration of edge placement error (EPE)means that a minimum pitch that is twice the wire width cannot be cutsince there is no possibility of stacking vertically in a single stack.For example, FIG. 18 illustrates an aperture 1800 of a BAA relative to aline 1802 to be cut or to have vias placed in targeted locations whilethe line is scanned along the direction of the arrow 1804 under theaperture 1800. Referring to FIG. 18, for a given line 1802 to be cut orvias to be placed, the EPE 1806 of the cutter opening (aperture) resultsin a rectangular opening in the BAA grid that is the pitch of the line.

FIG. 19 illustrates two non-staggered apertures 1900 and 1902 of a BAArelative to two lines 1904 and 1906, respectively, to be cut or to havevias placed in targeted locations while the lines are scanned along thedirection of the arrow 1908 under the apertures 1900 and 1902. Referringto FIG. 19, when the rectangular opening 1800 of FIG. 18 is placed in avertical single column with other such rectangular openings (e.g., nowas 1900 and 1902), the allowed pitch of the lines to be cut is limitedby 2×EPE 1910 plus the distance requirement 1912 between the BAA opens1900 and 1902 plus the width of one wire 1904 or 1906. The resultingspacing 1914 is shown by the arrow on the far right of FIG. 19. Such alinear array would severely limit the pitch of the wiring to besubstantially greater than 3-4× of the width of the wires, which may beunacceptable. Another unacceptable alternative would be to cut tighterpitch wires in two (or more) passes with slightly offset wire locations;this approach could severely limit the throughput of the ebeam machine.

By contrast to FIG. 19, FIG. 20 illustrates two columns 2002 and 2004 ofstaggered apertures 2006 of a BAA 2000 relative to a plurality of lines2008 to be cut or to have vias placed in targeted locations while thelines 2008 are scanned along the direction 2010 under the apertures2006, with scanning direction shown by the arrow, in accordance with anembodiment of the present invention. Referring to FIG. 19, a staggeredBAA 2000 includes two linear arrays 2002 and 2004, staggered spatiallyas shown. The two staggered arrays 2002 and 2004 cut (or place vias at)alternate lines 2008. The lines 2008 are, in one embodiment, placed on atight grid at twice the wire width. As used throughout the presentdisclosure, the term staggered array can refer to a staggering ofopenings 2006 that stagger in one direction (e.g., the verticaldirection) and either have no overlap or have some overlap when viewedas scanning in the orthogonal direction (e.g., the horizontaldirection). In the latter case, the effective overlap provides fortolerance in misalignment.

It is to be appreciated that, although a staggered array is shown hereinas two vertical columns for simplicity, the openings or apertures of asingle “column” need not be columnar in the vertical direction. Forexample, in an embodiment, so long as a first array collectively has apitch in the vertical direction, and a second array staggered in thescan direction from the first array collectively has the pitch in thevertical direction, the a staggered array is achieved. Thus, referenceto or depiction of a vertical column herein can actually be made up ofone or more columns unless specified as being a single column ofopenings or apertures. In one embodiment, in the case that a “column” ofopenings is not a single column of openings, any offset within the“column” can be compensated with strobe timing. In an embodiment, thecritical point is that the openings or apertures of a staggered array ofa BAA lie on a specific pitch in the first direction, but are offset inthe second direction to allow them to place cuts or vias without any gapbetween cuts or vias in the first direction.

Thus, one or more embodiments are directed to a staggered beam aperturearray where openings are staggered to allow meeting EPE cuts and/or viarequirements as opposed to an inline arrangement that cannot accommodatefor EPE technology needs. By contrast, with no stagger, the problem ofedge placement error (EPE) means that a minimum pitch that is twice thewire width cannot be cut since there is no possibility of stackingvertically in single stack. Instead, in an embodiment, use of astaggered BAA enables much greater than 4000 times faster thanindividually ebeam writing each wire location. Furthermore, a staggeredarray allows a wire pitch to be twice the wire width. In a particularembodiment, an array has 4096 staggered openings over two columns suchthat EPE for each of the cut and via locations can be made. It is to beappreciated that a staggered array, as contemplated herein, may includetwo or more columns of staggered openings.

In an embodiment, use of a staggered array leaves space for includingmetal around the apertures of the BAA which contain one or twoelectrodes for passing or steering the ebeam to the wafer or steering toa Faraday cup or blanking aperture. That is, each opening may beseparately controlled by electrodes to pass or deflect the ebeam. In oneembodiment, the BAA has 4096 openings, and the ebeam apparatus coversthe entire array of 4096 openings, with each opening electricallycontrolled. Throughput improvements are enabled by sweeping the waferunder the opening as shown by the thick black arrows.

In a particular embodiment, a staggered BAA has two rows of staggeredBAA openings. Such an array permits tight pitch wires, where wire pitchcan be 2× the wire width. Furthermore, all wires can be cut in a singlepass (or vias can be made in a single pass), thereby enabling throughputon the ebeam machine. FIG. 21A illustrates two columns of staggeredapertures (left) of a BAA relative to a plurality of lines (right)having cuts (breaks in the horizontal lines) or vias (filled-in boxes)patterned using the staggered BAA, with scanning direction shown by thearrow, in accordance with an embodiment of the present invention.

Referring to FIG. 21A, the line result from a single staggered arraycould be as depicted, where lines are of single pitch, with cuts andvias patterned. In particular, FIG. 21A depicts a plurality of lines2100 or open line positions 2102 where no lines exist. Vias 2104 andcuts 2106 may be formed along lines 2100. The lines 2100 are shownrelative to a BAA 2110 having a scanning direction 2112. Thus, FIG. 21Amay be viewed as a typical pattern produced by a single staggered array.Dotted lines show where cuts occurred in the patterned lines (includingtotal cut to remove a full line or line portion). The via locations 2104are patterning vias that land on top of the wires 2100.

In an embodiment, all or some of the openings or apertures of the BAA2110 can be switched open or “closed” (e.g., beam deflecting) as thewafer/die moves underneath along the wafer travel direction 2112. In anembodiment, the BAA can be independently controlled as to whether eachopening passes the ebeam through to the sample or deflects the beaminto, e.g., a Faraday cup or blanking aperture. The apparatus may bebuilt to deflect the overall beam coverage to just a portion of the BAA,and then individual openings in the BAA are electrically configured topass the ebeam (“on”) or not pass (“off”). It is to be appreciated thatreference to “openings” or “opening heights” refers to the spot sizeimpinged on the receiving wafer and not to the physical opening in theBAA since the physical openings are substantially larger (e.g., micronscale) than the spot size (e.g., nanometer scale) ultimately generatedfrom the BAA. Thus, when described herein as the pitch of a BAA orcolumn of openings in a BAA being said to “correspond” to the pitch ofmetal lines, such description actually refers to the relationshipbetween pitch of the impinging spots as generated from the BAA and thepitch of the lines being cut. As an example, the spots generated fromthe BAA 2110 have a pitch the same as the pitch of the lines 2100 (whenboth columns of BAA openings are considered together). Meanwhile, thespots generated from only one column of the staggered array of the BAA2110 have twice the pitch as the pitch of the lines 2100.

It is also to be appreciated that an ebeam column that includes astaggered beam aperture array (staggered BAA) as described above mayalso include other features in addition to those described inassociation with FIG. 4, some examples of which are further described ingreater detail below in association with FIGS. 24A-24C. For example, inan embodiment, the sample stage can be rotated by 90 degrees toaccommodate alternating metallization layers which may be printedorthogonally to one another (e.g., rotated between X and Y scanningdirections). In another embodiment, an e-beam tool is capable ofrotating a wafer by 90 degrees prior to loading the wafer on the stage.

FIG. 21B illustrates a cross-sectional view of a stack 2150 ofmetallization layers 2152 in an integrated circuit based on metal linelayouts of the type illustrated in FIG. 21A, in accordance with anembodiment of the present invention. Referring to FIG. 21B, in anexemplary embodiment, a metal cross-section for an interconnect stack2150 is derived from a single BAA array for the lower eight matchedmetal layers 2154, 2156, 2158, 2160, 2162, 2164, 2166 and 2168. It is tobe appreciated that upper thicker/wider metal lines 2170 and 2172 wouldnot be made with the single BAA. Via locations 2174 are depicted asconnecting the lower eight matched metal layers 2154, 2156, 2158, 2160,2162, 2164, 2166 and 2168.

In a fifth aspect of embodiments of the present invention, a three beamaperture array for an ebeam tool is described.

In an embodiment, a beam aperture array is implemented to solvethroughput of an ebeam machine while also enabling minimum wire pitch.As described above, with no stagger, the problem of edge placement error(EPE) means that a minimum pitch that is twice the wire width cannot becut since there is no possibility of stacking vertically in singlestack. Embodiments described below extend the staggered BAA concept topermit three separate pitches to be exposed on a wafer, either throughthree passes, or by illuminating/controlling all three beam aperturearrays simultaneously in a single pass. The latter approach may bepreferable for achieving the best throughput.

In some implementations, a three staggered beam aperture array is usedinstead of a single beam aperture array. The pitches of the threedifferent arrays may either be related (e.g., 10-20-30) or unrelatedpitches. The three pitches can be used in three separate regions on thetarget die, or the three pitches may occur simultaneously in the samelocalized region.

To provide context, the use of two or more single arrays would require aseparate ebeam apparatus, or a change out of the beam aperture array foreach different hole size/wire pitch. The result would otherwise be athroughput limiter and/or a cost of ownership issue. Instead,embodiments described herein are directed to BAAs having more than one(e.g., three) staggered array. In one such embodiment (in the case ofincluding three arrays on one BAA), three different arrays of pitchescan be patterned on a wafer without loss of throughput. Furthermore, thebeam pattern may be steered to cover one of the three arrays. Anextension of this technique can be used to pattern any mixture ofdifferent pitches by turning on and off the blanker holes in all threearrays as needed.

As an example, FIG. 22 illustrates apertures of a BAA 2200 having alayout of three different staggered arrays, in accordance with anembodiment of the present invention. Referring to FIG. 22, athree-column 2202, 2204 and 2206 blanker aperture array 2200 can be usedfor three different line pitches for cutting or making vias by all orsome of the apertures 2208 which are switched open or “closed” (beamdeflecting) as the wafer/die moves underneath along the wafer traveldirection 2210. In one such embodiment, multiple pitches can bepatterned without changing the BAA plate in the device. Furthermore, ina particular embodiment, multiple pitches can be printed at the sametime. Both techniques allow many spots to be printed during a continuouspass of the wafer under the BAA. It is to be appreciated that while thefocus of the description is on three separate columns of differentpitches, embodiments can be extended to include any number of pitchesthat can fit within the apparatus, e.g., 1, 2, 3, 4, 5, etc.

In an embodiment, the BAA can be independently controlled as to whethereach opening passes the ebeam or deflects the beam into a Faraday cup orblanking aperture. The apparatus may be built to deflect the overallbeam coverage to just a single pitch column, and then individualopenings in the pitch column are electrically configured to pass theebeam (“on”) or not pass (“off”). As an example, FIG. 23 illustratesapertures 2308 of a BAA 2300 having a layout of three differentstaggered arrays 2302, 2304 and 2306, where the ebeam covers only one ofthe arrays (e.g., array 2304), in accordance with an embodiment of thepresent invention. In such an apparatus configuration, throughput couldbe gained for specific areas on a die that contain only a single pitch.The direction of travel of the underlying wafer is indicated by arrow2310.

In one embodiment, in order to switch between pitch arrays, a deflectorcan be added to the ebeam column to allow the ebeam to be steerable ontothe BAA pitch array. As an example, FIG. 24A includes a cross-sectionalschematic representation of an ebeam column of an electron beamlithography apparatus having a deflector to shift the beam, inaccordance with an embodiment of the present invention. Referring toFIG. 24A, an ebeam column 2400, such as described in association withFIG. 4, includes a deflector 2402. The deflector can be used to shiftthe beam onto an appropriate pitch/cut row in a shaping aperturecorresponding to an appropriate array of a BAA 2404 having multiplepitch arrays. As an example, FIG. 24B illustrates a three (or up to n)pitch array for a BAA 2450 having pitch #1, cut #1 (2452), a pitch #2,cut #2 (2454) and a pitch # N, cut # N (2456). It is to be appreciatedthat the height of cut#n is not equal to the height of cut#n+m.

Other features may also be included in the ebeam column 2400. Forexample, further referring to FIG. 24A, in an embodiment, the stage canbe rotated by 90 degrees to accommodate alternating metallization layerswhich may be printed orthogonally to one another (e.g., rotated betweenX and Y scanning directions). In another embodiment, an e-beam tool iscapable of rotating a wafer by 90 degrees prior to loading the wafer onthe stage. In yet another example, FIG. 24C illustrates a zoom in slit2460 for inclusion on an ebeam column. The positioning of such a zoom inslit 2460 on column 2400 is shown in FIG. 24A. The zoom in slit 2460 maybe included to keep efficiency for different cut heights. It is to beappreciated that one or more of the above described features may beincluded in a single ebeam column.

In another embodiment, the ebeam fully illuminates multiple or allcolumns of pitches on the BAA. In such a configuration, all of theilluminated BAA openings would be electrically controlled to be “open”to pass the ebeam to the die, or “off” to prevent the ebeam fromreaching the die. The advantage of such an arrangement is that anycombination of holes could be used to print line cuts or via locationswithout reducing throughput. While the arrangement described inassociation with FIGS. 23 and 24A-24C could also be used to produce asimilar result, a separate pass across the wafer/die for each of thepitch arrays would be required (which would reduce throughput by afactor of 1/n, where n is the number of pitch arrays on the BAA thatrequire printing).

FIG. 25 illustrates apertures of a BAA having a layout of threedifferent pitch staggered arrays, where the ebeam covers all of thearrays, in accordance with an embodiment of the present invention.Referring to FIG. 25, apertures 2508 of a BAA 2500 having a layout ofthree different staggered arrays 2502, 2504 and 2506, where the ebeamcan cover all of the arrays (e.g., covers arrays 2502, 2504 and 2506),in accordance with an embodiment of the present invention. The directionof travel of the underlying wafer is indicated by arrow 2510.

In either the case of FIG. 23 or FIG. 25, having three pitches ofopenings permits the cutting or via creation for three different line orwire widths. However, the lines must be in alignment with the aperturesof the corresponding pitch array (by contrast, a universal cutter isdisclosed below). FIG. 26 illustrates a three beam staggered aperturearray 2600 of a BAA relative to a plurality of large lines 2602 havingcuts (e.g., breaks 2604 in the horizontal lines) or vias (filled-inboxes 2606) patterned using the BAA, with scanning direction shown bythe arrow 2608, in accordance with an embodiment of the presentinvention. Referring to FIG. 26, all the lines in a local region are ofthe same size (in this case, corresponding to the largest apertures 2610on the right side of the BAA). Thus, FIG. 26 illustrates a typicalpattern produced by one of three staggered beam aperture arrays. Dottedlines show where cuts occurred in patterned lines. Dark rectangles arepatterning vias that land on top of the lines/wires 2602. In this case,only the largest blanker array is enabled.

FIG. 27 illustrates a three beam staggered aperture array 2700 of a BAArelative to a plurality of medium sized lines 2702 having cuts (e.g.,breaks 2704 in the horizontal lines) or vias (filled-in boxes 2706)patterned using the BAA, with scanning direction shown by the arrow2708, in accordance with an embodiment of the present invention.Referring to FIG. 27, all the lines in a local region are of the samesize (in this case, corresponding to the medium sized apertures 2710 inthe middle of the BAA). Thus, FIG. 27 illustrates a typical patternproduced by one of three staggered beam aperture arrays. Dotted linesshow where cuts occurred in patterned lines. Dark rectangles arepatterning vias that land on top of the lines/wires 2702. In this case,only the medium blanker array is enabled.

FIG. 28 illustrates a three beam staggered aperture array 2800 of a BAArelative to a plurality of small lines 2802 having cuts (e.g., breaks2804 in the horizontal lines) or vias (filled-in boxes 2806) patternedusing the BAA, with scanning direction shown by the arrow 2808, inaccordance with an embodiment of the present invention. Referring toFIG. 28, all the lines in a local region are of the same size (in thiscase, corresponding to the smallest apertures 2810 on the left side ofthe BAA). Thus, FIG. 28 illustrates a typical pattern produced by one ofthree staggered beam aperture arrays. Dotted lines show where cutsoccurred in patterned lines. Dark rectangles are patterning vias thatland on top of the lines/wires 2802. In this case, only the smallblanker array is enabled.

In another embodiment, combinations of the three pitches can bepatterned, where the aperture alignment is possible against the linesalready in these positions. FIG. 29A illustrates a three beam staggeredaperture array 2900 of a BAA relative to a plurality of lines 2902 ofvarying size having cuts (e.g., breaks 2904 in the horizontal lines) orvias (filled-in boxes 2906) patterned using the BAA, with scanningdirection shown by the arrow 2908, in accordance with an embodiment ofthe present invention. Referring to FIG. 29A, as many as three differentmetal widths can be patterned on the fixed grids 2950 that occur on thethree-staggered BAA. The dark colored apertures 2910 of the BAA arebeing turned on/off during they scan. The light colored BAA apertures2912 remain off. Thus, FIG. 29A illustrates a typical pattern producedby simultaneous use of all three staggered beam aperture arrays. Dottedlines show where cuts occurred in patterned lines. Dark rectangles arepatterning vias that land on top of the lines/wires 2902. In this case,the small blanker array, the medium blanker array and the large blankerarray are all enabled.

FIG. 29B illustrates a cross-sectional view of a stack 2960 ofmetallization layers in an integrated circuit based on metal linelayouts of the type illustrated in FIG. 29A, in accordance with anembodiment of the present invention. Referring to FIG. 29B, in anexemplary embodiment, a metal cross-section for an interconnect stack isderived from three BAA pitch arrays of 1×, 1.5× and 3× pitch/width forthe lower eight matched levels 2962, 2964, 2966, 2968, 2970, 2972, 2974and 2976. For example, in level 2962, exemplary lines 2980 of 1×, anexemplary line 2982 of 1.5×, and an exemplary line 2984 of 3× are calledout. It is to be appreciated that the varying width for the metals canonly be seen for those layers with lines coming out of the page. Allmetals in the same layer are the same thickness regardless of metalwidth. It is to be appreciated that upper thicker/wider metals would notbe made with the same three pitch BAA.

In another embodiment, different lines within the array can changewidth. FIG. 30 illustrates a three beam staggered aperture array 3000 ofa BAA relative to a plurality of lines 3002 of varying size having cuts(e.g., breaks 3004 in the horizontal lines) or vias (filled-in boxes3006) patterned using the BAA, with scanning direction shown by thearrow 3008, in accordance with an embodiment of the present invention.Referring to FIG. 30, the third horizontal line 3050 from the bottom ofthe array of lines 3002 has a wide line 3052 on a same grid line 3056 asa narrow line 3054. The corresponding different sized, but horizontallyaligned, apertures 3060 and 3062 used to cut or make vias in thedifferent sized lines are highlighted and horizontally centered with thetwo lines 3052 and 3054. Thus, FIG. 30 illustrates a scenario with theadditional possibility to change line widths during patterning, as wellas within different regions.

In a sixth aspect of embodiments of the present invention, anon-universal cutter for an ebeam tool is described.

In an embodiment, the cutting of multiple pitches of wires in the sameregion is made possible. In a particular implementation, high throughputebeam processing is used to define cuts with two BAA arrays each withopening heights equal to predetermined values. As an illustrativeexample, N(20 nm-minimal layout pitch) and M(30 nm) can cut multiplepitch layouts (N[20], M[30], N*2[40], N*3 or M*2[60], N*4[80], M*3[90]nm) etc. with required EPE tolerance of minimum pitch/4 (N/4) providedthat cut/plug tracks are placed on grids.

FIG. 31 illustrates three sets of lines 3102, 3104 and 3106 of differingpitch with overlying corresponding apertures 3100 on each line, inaccordance with an embodiment of the present invention. Referring toFIG. 31, a 40 nm, 30 nm and 20 nm arrays vertical pitch is shown. Forthe 40 nm pitch lines 3102, a staggered BAA (e.g., having 2048 openings)is available for cutting the lines. For the 30 nm pitch lines 3104, astaggered BAA (e.g., having 2730 openings) is available for cutting thelines. For the 20 nm pitch lines 3106, a staggered BAA (e.g., having4096 openings) is available for cutting the lines. In this exemplarycase, parallel lines drawn on a 10 nm step unidirectional grid 3150 withpitches 20 nm, 30 nm and 40 nm need to be cut. The BAA has three pitches(i.e., three sub-arrays) and is axially aligned with drawn tracks 3160,as depicted in FIG. 31.

Provided each aperture on each of the three sub-arrays of FIG. 31 hasits own driver, cutting of complex layouts with tracks on a layoutconsistent with the depicted unidirectional grid can be performed withtool throughput independent of number and mix of pitches present in thelayout. The result is that multiple cuts, multiple simultaneous cuts ofdifferent widths, and cuts of widths that are greater than any singlepitch are made possible. The design may be referred to as pitch agnosticthroughput. To provide context, such a result is not possible wheremultiple passes of the wafer are required for each pitch. It is to beappreciated that such an implementation is not restricted to three BAAopening sizes. Additional combinations could be produced as long asthere is a common grid relationship between the various BAA pitches.

Furthermore, in an embodiment, multiple cuts made at the same time arepossible with multiple pitches, and wider lines are accommodated bycombinations of different openings that completely cover the cutdistance. For example, FIG. 32 illustrates a plurality of differentsized lines 3202 including one very large line 3204, and a beam aperturearrays vertical pitch layout 3206 (three arrays 3208, 3210 and 3212) ona common grid 3214, in accordance with an embodiment of the presentinvention. The very wide line 3204 is cut by a combination of threelarge apertures 3216 which are additive in the vertical direction. It isto be appreciated in viewing FIG. 32, the wires 3202 are shown as beingcut by various openings which are shown as dashed boxes (e.g., dashedboxes 3218 corresponding to apertures 3216).

In a seventh aspect of embodiments of the present invention, a universalcutter for an ebeam tool is described.

In an embodiment, high throughput ebeam processing is enabled bydefining cuts such that a single (universal) BAA having opening heightsequal to predetermined values can be used for a variety of linepitches/widths. In one such embodiment, the opening heights are targetedat half of the minimal pitch layout. It is to be appreciated thatreference to “opening heights” refers to the spot size impinged on thereceiving wafer and not to the physical opening in the BAA since thephysical openings are substantially larger (e.g., micron scale) than thespot size (e.g., nanometer scale) ultimately generated from the BAA. Ina particular example, the height of the openings is 10 nm for a minimallayout pitch of N=20 nm). In such a case, multiple pitch layouts (e.g.,N[20], M[30], N*2[40], N*3 or M*2[60], N*4[80], M*3[90] nm) etc. can becut. The cuts can be performed with a required EPE tolerance of minimumpitch/4 (N/4) provided cut/plug tracks are placed on a predeterminedgrid where tracks axes are aligned on a predetermined one-dimensional(1D) grid coincidental with the middle between two BAA openings. Eachmetal track adjacency is interrupted by exposing two openings at theminimum to satisfy an EPE requirement=pitch/4.

In an example, FIG. 33 illustrates a plurality of different sized lines3302, and a universal cutter pitch array 3304, in accordance with anembodiment of the present invention. Referring to FIG. 33, in aparticular embodiment, a BAA having a 10 nm pitch array 3304 with, e.g.,8192 openings (only a few of which are shown) is used as a universalcutter. It is to be appreciated that although shown on a common grid3306, in one embodiment, the lines need not actually be aligned to agrid at all. In that embodiment, spacing is differentiated by the cutteropenings.

More generally, referring again to FIG. 33, a beam aperture array 3304includes an array of staggered square beam openings 3308 (e.g., 8192staggered square beam openings) that can be implemented to cut any widthline/wire 3302 by using one or more of the openings in conjunction inthe vertical direction while the scan is performed along the horizontaldirection 3310. The only restriction is that adjacent wires be 2*EPE forcutting any individual wire. In one embodiment, the wires are cut bycombinations of universal cutter openings 3308 chosen on the fly fromthe BAA 3304. As an example, line 3312 is cut by three openings 3314from the BAA 3304. In another example, line 3316 is cut by 11 openings3318 from the BAA 3304.

For comparison to a non-universal cutter, a grouping of arrays 3320 isillustrated in FIG. 33. It is to be appreciated that the grouping ofarrays 3320 is not present in the universal cutter, but are shown forcomparison of the universal cutter to a non-universal cutter based onthe grouping of arrays 3320.

To provide context, other beam aperture array arrangements requireopenings that are specifically aligned on the centerline of the lines tobe cut. Instead, in accordance with an embodiment herein, a universalaperture array technique allows universal cutting of any width line/wireon non-aligned line centerlines. Furthermore, changes in line widths(and spacings) that would otherwise be fixed by the BAA of othertechniques are accommodated by the universal cutter. Accordingly, latechanges to a fabrication process, or lines/wires specifically tailoredto the RC needs of an individual circuit may be permitted.

It is to be appreciated that as long as the EPE coverage requirement ofpitch/4 is met, the various lines/wires do not have to be exactlyaligned in a universal cutter scenario. The only restrictions is thatsufficient enough space is provided between lines to have EPE/2 distancebetween lines with the cutter lining up at EPE/4 as follows. FIG. 34demonstrates the 2*EPE rule for a universal cutter 3400 as referencedagainst two lines 3402 and 3404, in accordance with an embodiment of thepresent invention. Referring to FIG. 34, the EPE 3406 of the top lineand the EPE 3408 of the bottom line provide the 2*EPE width whichcorresponds to the pitch of the universal cutter holes 3410. Thus, therule for opening pitch corresponds to the minimum space between twolines. If the distance is greater than this, the cutter will cut anyarbitrary width line. Note that the minimum hole size and pitch isexactly equal to 2*EPE for lines.

In an embodiment, by using a universal cutter, the resulting structurescan have random wire widths and placement in an ebeam-producedsemiconductor sample. The random placement, however, is still describedas unidirectional since no orthogonal lines or hooks are fabricated inthis approach. A universal cutter can be implemented for cutting manydifferent pitches and widths, e.g., whatever can be fabricated bypatterning prior to ebeam patterning used for cuts and vias. As acomparison, the above described staggered array and three-staggeredarray BAAs are associated with fixed locations for the pitches.

More generally, referring to all of the above aspects of embodiments ofthe present invention, it is to be appreciated that a metallizationlayer having lines with line cuts (or plugs) and having associated viasmay be fabricated above a substrate and, in one embodiment, may befabricated above a previous metallization layer. As an example, FIG. 35illustrates a plan view and corresponding cross-sectional view of aprevious layer metallization structure, in accordance with an embodimentof the present invention. Referring to FIG. 35, a starting structure3500 includes a pattern of metal lines 3502 and interlayer dielectric(ILD) lines 3504. The starting structure 3500 may be patterned in agrating-like pattern with metal lines spaced at a constant pitch andhaving a constant width, as is depicted in FIG. 35. Although not shown,the lines 3502 may have interruptions (i.e., cuts or plugs) at variouslocations along the lines. The pattern, for example, may be fabricatedby a pitch halving or pitch quartering approach, as described above.Some of the lines may be associated with underlying vias, such as line3502′ shown as an example in the cross-sectional view.

In an embodiment, fabrication of a metallization layer on the previousmetallization structure of FIG. 35 begins with formation of aninterlayer dielectric (ILD) material above the structure 3500. Ahardmask material layer may then be formed on the ILD layer. Thehardmask material layer may be patterned to form a grating ofunidirectional lines orthogonal to the lines 3502 of 3500. In oneembodiment, the grating of unidirectional hardmask lines is fabricatedusing conventional lithography (e.g., photoresist and other associatedlayers) and may have a line density defined by a pitch-halving,pitch-quartering etc. approach as described above. The grating ofhardmask lines leaves exposed a grating region of the underlying ILDlayer. It is these exposed portions of the ILD layer that are ultimatelypatterned for metal line formation, via formation, and plug formation.For example, in an embodiment, via locations are patterned in regions ofthe exposed ILD using EBL as described above. The patterning may involveformation of a resist layer and patterning of the resist layer by EBL toprovide via opening locations which may be etched into the ILD regions.The lines of overlying hardmask can be used to confine the vias to onlyregions of the exposed ILD, with overlap accommodated by the hardmasklines which can effectively be used as an etch stop. Plug (or cut)locations may also be patterned in exposed regions of the ILD, asconfined by the overlying hardmask lines, in a separate EBL processingoperation. The fabrication of cuts or plugs effectively preserve regionsof ILD that will ultimately interrupt metal lines fabricated therein.Metal lines may then be fabricated using a damascene approach, whereexposed portions of the ILD (those portions between the hardmask linesand not protected by a plug preservation layer, such as a resist layerpatterned during “cutting”) are partially recessed. The recessing mayfurther extend the via locations to open metal lines from the underlyingmetallization structure. The partially recessed ILD regions are thenfilled with metal (a process which may also involve filling the vialocations), e.g., by plating and CMP processing, to provide metal linesbetween the overlying hardmask lines. The hardmask lines may ultimatelybe removed for completion of a metallization structure. It is to beappreciated that the above ordering of line cuts, via formation, andultimate line formation is provided only as an example. A variety ofprocessing schemes may be accommodated using EBL cuts and vias, asdescribed herein.

In an embodiment, as used throughout the present description, interlayerdielectric (ILD) material is composed of or includes a layer of adielectric or insulating material. Examples of suitable dielectricmaterials include, but are not limited to, oxides of silicon (e.g.,silicon dioxide (SiO₂)), doped oxides of silicon, fluorinated oxides ofsilicon, carbon doped oxides of silicon, various low-k dielectricmaterials known in the arts, and combinations thereof. The interlayerdielectric material may be formed by conventional techniques, such as,for example, chemical vapor deposition (CVD), physical vapor deposition(PVD), or by other deposition methods.

In an embodiment, as is also used throughout the present description,interconnect material is composed of one or more metal or otherconductive structures. A common example is the use of copper lines andstructures that may or may not include barrier layers between the copperand surrounding ILD material. As used herein, the term metal includesalloys, stacks, and other combinations of multiple metals. For example,the metal interconnect lines may include barrier layers, stacks ofdifferent metals or alloys, etc. The interconnect lines are alsosometimes referred to in the arts as traces, wires, lines, metal, orsimply interconnect.

In an embodiment, as is also used throughout the present description,hardmask materials are composed of dielectric materials different fromthe interlayer dielectric material. In some embodiments, a hardmasklayer includes a layer of a nitride of silicon (e.g., silicon nitride)or a layer of an oxide of silicon, or both, or a combination thereof.Other suitable materials may include carbon-based materials. In anotherembodiment, a hardmask material includes a metal species. For example, ahardmask or other overlying material may include a layer of a nitride oftitanium or another metal (e.g., titanium nitride). Potentially lesseramounts of other materials, such as oxygen, may be included in one ormore of these layers. Alternatively, other hardmask layers known in thearts may be used depending upon the particular implementation. Thehardmask layers maybe formed by CVD, PVD, or by other depositionmethods.

It is to be appreciated that the layers and materials described inassociation with FIG. 35 are typically formed on or above an underlyingsemiconductor substrate or structure, such as underlying device layer(s)of an integrated circuit. In an embodiment, an underlying semiconductorsubstrate represents a general workpiece object used to manufactureintegrated circuits. The semiconductor substrate often includes a waferor other piece of silicon or another semiconductor material. Suitablesemiconductor substrates include, but are not limited to, single crystalsilicon, polycrystalline silicon and silicon on insulator (SOI), as wellas similar substrates formed of other semiconductor materials. Thesemiconductor substrate, depending on the stage of manufacture, oftenincludes transistors, integrated circuitry, and the like. The substratemay also include semiconductor materials, metals, dielectrics, dopants,and other materials commonly found in semiconductor substrates.Furthermore, the structure depicted in FIG. 35 may be fabricated onunderlying lower level interconnect layers.

In another embodiment, EBL cuts may be used to fabricate semiconductordevices, such as PMOS or NMOS devices of an integrated circuit. In onesuch embodiment, EBL cuts are used to pattern a grating of activeregions that are ultimately used to form fin-based or trigatestructures. In another such embodiment, EBL cuts are used to pattern agate layer, such as a poly layer, ultimately used for gate electrodefabrication. As an example of a completed device, FIGS. 36A and 36Billustrate a cross-sectional view and a plan view (taken along the a-a′axis of the cross-sectional view), respectively, of a non-planarsemiconductor device having a plurality of fins, in accordance with anembodiment of the present invention.

Referring to FIG. 36A, a semiconductor structure or device 3600 includesa non-planar active region (e.g., a fin structure including protrudingfin portion 3604 and sub-fin region 3605) formed from substrate 3602,and within isolation region 3606. A gate line 3608 is disposed over theprotruding portions 3604 of the non-planar active region as well as overa portion of the isolation region 3606. As shown, gate line 3608includes a gate electrode 3650 and a gate dielectric layer 3652. In oneembodiment, gate line 3608 may also include a dielectric cap layer 3654.A gate contact 3614, and overlying gate contact via 3616 are also seenfrom this perspective, along with an overlying metal interconnect 3660,all of which are disposed in inter-layer dielectric stacks or layers3670. Also seen from the perspective of FIG. 36A, the gate contact 3614is, in one embodiment, disposed over isolation region 3606, but not overthe non-planar active regions.

Referring to FIG. 36B, the gate line 3608 is shown as disposed over theprotruding fin portions 3604. Source and drain regions 3604A and 3604Bof the protruding fin portions 3604 can be seen from this perspective.In one embodiment, the source and drain regions 3604A and 3604B aredoped portions of original material of the protruding fin portions 3604.In another embodiment, the material of the protruding fin portions 3604is removed and replaced with another semiconductor material, e.g., byepitaxial deposition. In either case, the source and drain regions 3604Aand 3604B may extend below the height of dielectric layer 3606, i.e.,into the sub-fin region 3605.

In an embodiment, the semiconductor structure or device 3600 is anon-planar device such as, but not limited to, a fin-FET or a tri-gatedevice. In such an embodiment, a corresponding semiconducting channelregion is composed of or is formed in a three-dimensional body. In onesuch embodiment, the gate electrode stacks of gate lines 3608 surroundat least a top surface and a pair of sidewalls of the three-dimensionalbody.

Embodiments disclosed herein may be used to manufacture a wide varietyof different types of integrated circuits and/or microelectronicdevices. Examples of such integrated circuits include, but are notlimited to, processors, chipset components, graphics processors, digitalsignal processors, micro-controllers, and the like. In otherembodiments, semiconductor memory may be manufactured. Moreover, theintegrated circuits or other microelectronic devices may be used in awide variety of electronic devices known in the arts. For example, incomputer systems (e.g., desktop, laptop, server), cellular phones,personal electronics, etc. The integrated circuits may be coupled with abus and other components in the systems. For example, a processor may becoupled by one or more buses to a memory, a chipset, etc. Each of theprocessor, the memory, and the chipset, may potentially be manufacturedusing the approaches disclosed herein.

FIG. 37 illustrates a computing device 3700 in accordance with oneimplementation of the invention. The computing device 3700 houses aboard 3702. The board 3702 may include a number of components, includingbut not limited to a processor 3704 and at least one communication chip3706. The processor 3704 is physically and electrically coupled to theboard 3702. In some implementations the at least one communication chip3706 is also physically and electrically coupled to the board 3702. Infurther implementations, the communication chip 3706 is part of theprocessor 3704.

Depending on its applications, computing device 3700 may include othercomponents that may or may not be physically and electrically coupled tothe board 3702. These other components include, but are not limited to,volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flashmemory, a graphics processor, a digital signal processor, a cryptoprocessor, a chipset, an antenna, a display, a touchscreen display, atouchscreen controller, a battery, an audio codec, a video codec, apower amplifier, a global positioning system (GPS) device, a compass, anaccelerometer, a gyroscope, a speaker, a camera, and a mass storagedevice (such as hard disk drive, compact disk (CD), digital versatiledisk (DVD), and so forth).

The communication chip 3706 enables wireless communications for thetransfer of data to and from the computing device 3700. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 3706 may implementany of a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 3700 may include a plurality ofcommunication chips 3706. For instance, a first communication chip 3706may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 3706 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 3704 of the computing device 3700 includes an integratedcircuit die packaged within the processor 3704. In some implementationsof the invention, the integrated circuit die of the processor includesone or more structures fabricated using CEBL, in accordance withimplementations of embodiments of the invention. The term “processor”may refer to any device or portion of a device that processes electronicdata from registers and/or memory to transform that electronic data intoother electronic data that may be stored in registers and/or memory.

The communication chip 3706 also includes an integrated circuit diepackaged within the communication chip 3706. In accordance with anotherimplementation of embodiments of the invention, the integrated circuitdie of the communication chip includes one or more structures fabricatedusing CEBL, in accordance with implementations of embodiments of theinvention.

In further implementations, another component housed within thecomputing device 3700 may contain an integrated circuit die thatincludes one or more structures fabricated using CEBL, in accordancewith implementations of embodiments of the invention.

In various implementations, the computing device 3700 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 3700 may be any other electronic device that processes data.

Embodiments of the present invention may be provided as a computerprogram product, or software, that may include a machine-readable mediumhaving stored thereon instructions, which may be used to program acomputer system (or other electronic devices) to perform a processaccording to embodiments of the present invention. In one embodiment,the computer system is coupled with an ebeam tool such as described inassociation with FIG. 4 and/or FIGS. 24A-24C. A machine-readable mediumincludes any mechanism for storing or transmitting information in a formreadable by a machine (e.g., a computer). For example, amachine-readable (e.g., computer-readable) medium includes a machine(e.g., a computer) readable storage medium (e.g., read only memory(“ROM”), random access memory (“RAM”), magnetic disk storage media,optical storage media, flash memory devices, etc.), a machine (e.g.,computer) readable transmission medium (electrical, optical, acousticalor other form of propagated signals (e.g., infrared signals, digitalsignals, etc.)), etc.

FIG. 38 illustrates a diagrammatic representation of a machine in theexemplary form of a computer system 3800 within which a set ofinstructions, for causing the machine to perform any one or more of themethodologies described herein (such as end-point detection), may beexecuted. In alternative embodiments, the machine may be connected(e.g., networked) to other machines in a Local Area Network (LAN), anintranet, an extranet, or the Internet. The machine may operate in thecapacity of a server or a client machine in a client-server networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment. The machine may be a personal computer (PC), atablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), acellular telephone, a web appliance, a server, a network router, switchor bridge, or any machine capable of executing a set of instructions(sequential or otherwise) that specify actions to be taken by thatmachine. Further, while only a single machine is illustrated, the term“machine” shall also be taken to include any collection of machines(e.g., computers) that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies described herein.

The exemplary computer system 3800 includes a processor 3802, a mainmemory 3804 (e.g., read-only memory (ROM), flash memory, dynamic randomaccess memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM(RDRAM), etc.), a static memory 3806 (e.g., flash memory, static randomaccess memory (SRAM), etc.), and a secondary memory 3818 (e.g., a datastorage device), which communicate with each other via a bus 3830.

Processor 3802 represents one or more general-purpose processing devicessuch as a microprocessor, central processing unit, or the like. Moreparticularly, the processor 3802 may be a complex instruction setcomputing (CISC) microprocessor, reduced instruction set computing(RISC) microprocessor, very long instruction word (VLIW) microprocessor,processor implementing other instruction sets, or processorsimplementing a combination of instruction sets. Processor 3802 may alsobe one or more special-purpose processing devices such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), a digital signal processor (DSP), network processor, or thelike. Processor 3802 is configured to execute the processing logic 3826for performing the operations described herein.

The computer system 3800 may further include a network interface device3808. The computer system 3800 also may include a video display unit3810 (e.g., a liquid crystal display (LCD), a light emitting diodedisplay (LED), or a cathode ray tube (CRT)), an alphanumeric inputdevice 3812 (e.g., a keyboard), a cursor control device 3814 (e.g., amouse), and a signal generation device 3816 (e.g., a speaker).

The secondary memory 3818 may include a machine-accessible storagemedium (or more specifically a computer-readable storage medium) 3832 onwhich is stored one or more sets of instructions (e.g., software 3822)embodying any one or more of the methodologies or functions describedherein. The software 3822 may also reside, completely or at leastpartially, within the main memory 3804 and/or within the processor 3802during execution thereof by the computer system 3800, the main memory3804 and the processor 3802 also constituting machine-readable storagemedia. The software 3822 may further be transmitted or received over anetwork 3820 via the network interface device 3808.

While the machine-accessible storage medium 3832 is shown in anexemplary embodiment to be a single medium, the term “machine-readablestorage medium” should be taken to include a single medium or multiplemedia (e.g., a centralized or distributed database, and/or associatedcaches and servers) that store the one or more sets of instructions. Theterm “machine-readable storage medium” shall also be taken to includeany medium that is capable of storing or encoding a set of instructionsfor execution by the machine and that cause the machine to perform anyone or more of the methodologies of the present invention. The term“machine-readable storage medium” shall accordingly be taken to include,but not be limited to, solid-state memories, and optical and magneticmedia.

Implementations of embodiments of the invention may be formed or carriedout on a substrate, such as a semiconductor substrate. In oneimplementation, the semiconductor substrate may be a crystallinesubstrate formed using a bulk silicon or a silicon-on-insulatorsubstructure. In other implementations, the semiconductor substrate maybe formed using alternate materials, which may or may not be combinedwith silicon, that include but are not limited to germanium, indiumantimonide, lead telluride, indium arsenide, indium phosphide, galliumarsenide, indium gallium arsenide, gallium antimonide, or othercombinations of group III-V or group IV materials. Although a fewexamples of materials from which the substrate may be formed aredescribed here, any material that may serve as a foundation upon which asemiconductor device may be built falls within the spirit and scope ofthe present invention.

A plurality of transistors, such as metal-oxide-semiconductorfield-effect transistors (MOSFET or simply MOS transistors), may befabricated on the substrate. In various implementations of theinvention, the MOS transistors may be planar transistors, nonplanartransistors, or a combination of both. Nonplanar transistors includeFinFET transistors such as double-gate transistors and tri-gatetransistors, and wrap-around or all-around gate transistors such asnanoribbon and nanowire transistors. Although the implementationsdescribed herein may illustrate only planar transistors, it should benoted that the invention may also be carried out using nonplanartransistors.

Each MOS transistor includes a gate stack formed of at least two layers,a gate dielectric layer and a gate electrode layer. The gate dielectriclayer may include one layer or a stack of layers. The one or more layersmay include silicon oxide, silicon dioxide (SiO₂) and/or a high-kdielectric material. The high-k dielectric material may include elementssuch as hafnium, silicon, oxygen, titanium, tantalum, lanthanum,aluminum, zirconium, barium, strontium, yttrium, lead, scandium,niobium, and zinc. Examples of high-k materials that may be used in thegate dielectric layer include, but are not limited to, hafnium oxide,hafnium silicon oxide, lanthanum oxide, lanthanum aluminum oxide,zirconium oxide, zirconium silicon oxide, tantalum oxide, titaniumoxide, barium strontium titanium oxide, barium titanium oxide, strontiumtitanium oxide, yttrium oxide, aluminum oxide, lead scandium tantalumoxide, and lead zinc niobate. In some embodiments, an annealing processmay be carried out on the gate dielectric layer to improve its qualitywhen a high-k material is used.

The gate electrode layer is formed on the gate dielectric layer and mayconsist of at least one P-type workfunction metal or N-type workfunctionmetal, depending on whether the transistor is to be a PMOS or an NMOStransistor. In some implementations, the gate electrode layer mayconsist of a stack of two or more metal layers, where one or more metallayers are workfunction metal layers and at least one metal layer is afill metal layer.

For a PMOS transistor, metals that may be used for the gate electrodeinclude, but are not limited to, ruthenium, palladium, platinum, cobalt,nickel, and conductive metal oxides, e.g., ruthenium oxide. A P-typemetal layer will enable the formation of a PMOS gate electrode with aworkfunction that is between about 4.9 eV and about 5.2 eV. For an NMOStransistor, metals that may be used for the gate electrode include, butare not limited to, hafnium, zirconium, titanium, tantalum, aluminum,alloys of these metals, and carbides of these metals such as hafniumcarbide, zirconium carbide, titanium carbide, tantalum carbide, andaluminum carbide. An N-type metal layer will enable the formation of anNMOS gate electrode with a workfunction that is between about 3.9 eV andabout 4.2 eV.

In some implementations, the gate electrode may consist of a “U”-shapedstructure that includes a bottom portion substantially parallel to thesurface of the substrate and two sidewall portions that aresubstantially perpendicular to the top surface of the substrate. Inanother implementation, at least one of the metal layers that form thegate electrode may simply be a planar layer that is substantiallyparallel to the top surface of the substrate and does not includesidewall portions substantially perpendicular to the top surface of thesubstrate. In further implementations of the invention, the gateelectrode may consist of a combination of U-shaped structures andplanar, non-U-shaped structures. For example, the gate electrode mayconsist of one or more U-shaped metal layers formed atop one or moreplanar, non-U-shaped layers.

In some implementations of the invention, a pair of sidewall spacers maybe formed on opposing sides of the gate stack that bracket the gatestack. The sidewall spacers may be formed from a material such assilicon nitride, silicon oxide, silicon carbide, silicon nitride dopedwith carbon, and silicon oxynitride. Processes for forming sidewallspacers are well known in the art and generally include deposition andetching process steps. In an alternate implementation, a plurality ofspacer pairs may be used, for instance, two pairs, three pairs, or fourpairs of sidewall spacers may be formed on opposing sides of the gatestack.

As is well known in the art, source and drain regions are formed withinthe substrate adjacent to the gate stack of each MOS transistor. Thesource and drain regions are generally formed using either animplantation/diffusion process or an etching/deposition process. In theformer process, dopants such as boron, aluminum, antimony, phosphorous,or arsenic may be ion-implanted into the substrate to form the sourceand drain regions. An annealing process that activates the dopants andcauses them to diffuse further into the substrate typically follows theion implantation process. In the latter process, the substrate may firstbe etched to form recesses at the locations of the source and drainregions. An epitaxial deposition process may then be carried out to fillthe recesses with material that is used to fabricate the source anddrain regions. In some implementations, the source and drain regions maybe fabricated using a silicon alloy such as silicon germanium or siliconcarbide. In some implementations the epitaxially deposited silicon alloymay be doped in situ with dopants such as boron, arsenic, orphosphorous. In further embodiments, the source and drain regions may beformed using one or more alternate semiconductor materials such asgermanium or a group III-V material or alloy. And in furtherembodiments, one or more layers of metal and/or metal alloys may be usedto form the source and drain regions.

One or more interlayer dielectrics (ILD) are deposited over the MOStransistors. The ILD layers may be formed using dielectric materialsknown for their applicability in integrated circuit structures, such aslow-k dielectric materials. Examples of dielectric materials that may beused include, but are not limited to, silicon dioxide (SiO₂), carbondoped oxide (CDO), silicon nitride, organic polymers such asperfluorocyclobutane or polytetrafluoroethylene, fluorosilicate glass(FSG), and organosilicates such as silsesquioxane, siloxane, ororganosilicate glass. The ILD layers may include pores or air gaps tofurther reduce their dielectric constant.

FIG. 39 illustrates an interposer 3900 that includes one or moreembodiments of the invention. The interposer 3900 is an interveningsubstrate used to bridge a first substrate 3902 to a second substrate3904. The first substrate 3902 may be, for instance, an integratedcircuit die. The second substrate 3904 may be, for instance, a memorymodule, a computer motherboard, or another integrated circuit die.Generally, the purpose of an interposer 3900 is to spread a connectionto a wider pitch or to reroute a connection to a different connection.For example, an interposer 3900 may couple an integrated circuit die toa ball grid array (BGA) 3906 that can subsequently be coupled to thesecond substrate 3904. In some embodiments, the first and secondsubstrates 3902/3904 are attached to opposing sides of the interposer3900. In other embodiments, the first and second substrates 3902/3904are attached to the same side of the interposer 3900. And in furtherembodiments, three or more substrates are interconnected by way of theinterposer 3900.

The interposer 3900 may be formed of an epoxy resin, afiberglass-reinforced epoxy resin, a ceramic material, or a polymermaterial such as polyimide. In further implementations, the interposermay be formed of alternate rigid or flexible materials that may includethe same materials described above for use in a semiconductor substrate,such as silicon, germanium, and other group III-V and group IVmaterials.

The interposer may include metal interconnects 3908 and vias 3910,including but not limited to through-silicon vias (TSVs) 3912. Theinterposer 3900 may further include embedded devices 3914, includingboth passive and active devices. Such devices include, but are notlimited to, capacitors, decoupling capacitors, resistors, inductors,fuses, diodes, transformers, sensors, and electrostatic discharge (ESD)devices. More complex devices such as radio-frequency (RF) devices,power amplifiers, power management devices, antennas, arrays, sensors,and MEMS devices may also be formed on the interposer 3900.

In accordance with embodiments of the invention, apparatuses orprocesses disclosed herein may be used in the fabrication of interposer3900.

FIG. 40 illustrates a computing device 4000 in accordance with oneembodiment of the invention. The computing device 4000 may include anumber of components. In one embodiment, these components are attachedto one or more motherboards. In an alternate embodiment, thesecomponents are fabricated onto a single system-on-a-chip (SoC) dierather than a motherboard. The components in the computing device 4000include, but are not limited to, an integrated circuit die 4002 and atleast one communication chip 4008. In some implementations thecommunication chip 4008 is fabricated as part of the integrated circuitdie 4002. The integrated circuit die 4002 may include a CPU 4004 as wellas on-die memory 4006, often used as cache memory, that can be providedby technologies such as embedded DRAM (eDRAM) or spin-transfer torquememory (STTM or STTM-RAM).

Computing device 4000 may include other components that may or may notbe physically and electrically coupled to the motherboard or fabricatedwithin an SoC die. These other components include, but are not limitedto, volatile memory 4010 (e.g., DRAM), non-volatile memory 4012 (e.g.,ROM or flash memory), a graphics processing unit 4014 (GPU), a digitalsignal processor 4016, a crypto processor 4042 (a specialized processorthat executes cryptographic algorithms within hardware), a chipset 4020,an antenna 4022, a display or a touchscreen display 4024, a touchscreencontroller 4026, a battery 4029 or other power source, a power amplifier(not shown), a global positioning system (GPS) device 4028, a compass4030, a motion coprocessor or sensors 4032 (that may include anaccelerometer, a gyroscope, and a compass), a speaker 4034, a camera4036, user input devices 4038 (such as a keyboard, mouse, stylus, andtouchpad), and a mass storage device 4040 (such as hard disk drive,compact disk (CD), digital versatile disk (DVD), and so forth).

The communications chip 4008 enables wireless communications for thetransfer of data to and from the computing device 4000. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 4008 may implementany of a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 4000 may include a plurality ofcommunication chips 4008. For instance, a first communication chip 4008may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 4008 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 4004 of the computing device 4000 includes one or morestructures fabricated using CEBL, in accordance with implementations ofembodiments of the invention. The term “processor” may refer to anydevice or portion of a device that processes electronic data fromregisters and/or memory to transform that electronic data into otherelectronic data that may be stored in registers and/or memory.

The communication chip 4008 may also include one or more structuresfabricated using CEBL, in accordance with implementations of embodimentsof the invention.

In further embodiments, another component housed within the computingdevice 4000 may contain one or more structures fabricated using CEBL, inaccordance with implementations of embodiments of the invention.

In various embodiments, the computing device 4000 may be a laptopcomputer, a netbook computer, a notebook computer, an ultrabookcomputer, a smartphone, a tablet, a personal digital assistant (PDA), anultra mobile PC, a mobile phone, a desktop computer, a server, aprinter, a scanner, a monitor, a set-top box, an entertainment controlunit, a digital camera, a portable music player, or a digital videorecorder. In further implementations, the computing device 4000 may beany other electronic device that processes data.

The above description of illustrated implementations of embodiments ofthe invention, including what is described in the Abstract, is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. While specific implementations of, and examples for, theinvention are described herein for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize.

These modifications may be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific implementationsdisclosed in the specification and the claims. Rather, the scope of theinvention is to be determined entirely by the following claims, whichare to be construed in accordance with established doctrines of claiminterpretation.

In an embodiment, a method of real-time alignment of a wafer situated ona stage of an e-beam tool involves collecting backscattered electronsfrom an underlying patterned feature of the wafer while an e-beam columnof the e-beam tool writes during scanning of the stage. The collectingis performed by an electron detector placed at the e-beam column bottom.The method also involves performing corrections of an alignment of thestage relative to the e-beam column based on the collecting.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed at any point on apattern field of the e-beam column that includes the underlyingpatterned feature.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed at a plurality oflocations within a single die location, the plurality of locationscorresponding to a plurality of underlying alignment marks of theunderlying patterned feature.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed on the order ofhundreds of times within a single die location.

In one embodiment, time positions of an e-beam of the e-beam column areregistered against the plurality of underlying alignment marks of theunderlying patterned feature during scanning of the stage using drop incells.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes fitting polynomials.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes estimating complexcorrection parameters of higher orders.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes fitting polynomials andexcludes estimating complex correction parameters of higher orders.

In an embodiment, a column for e-beam tool includes an electron sourcefor providing a beam of electrons. The column also includes a limitingaperture coupled with the electron source along a pathway of the beam ofthe beam of electrons. The column also includes high aspect ratioillumination optics coupled with the limiting aperture along the pathwayof the beam of the beam of electrons. The column also includes a shapingaperture coupled with the high aspect ratio illumination optics alongthe pathway of the beam of the beam of electrons. The column alsoincludes a blanker aperture array (BAA) coupled with the shapingaperture along the pathway of the beam of the beam of electrons. Thecolumn also includes a final aperture coupled with the BAA along thepathway of the beam of the beam of electrons. The column also includes asample stage for receiving the beam of electrons. The column alsoincludes an electron detector for collecting backscattered electronsfrom an underlying patterned feature of a sample wafer on the samplestage while scanning the sample stage in a scan direction during ane-beam column writing operation, the e-beam column writing operationusing the beam of electrons.

In one embodiment, the BAA is a three beam staggered blanker aperturearray.

In one embodiment, the BAA is a universal cutter blanker aperture array.

In one embodiment, the BAA is a non-universal cutter blanker aperturearray.

In an embodiment, a non-transitory machine-accessible storage medium hasinstructions stored thereon which cause a data processing system toperform a method of real-time alignment of a wafer situated on a stageof an e-beam tool. The method involves collecting backscatteredelectrons from an underlying patterned feature of the wafer while ane-beam column of the e-beam tool writes during scanning of the stage.The collecting is performed by an electron detector placed at the e-beamcolumn bottom. The method also involves performing corrections of analignment of the stage relative to the e-beam column based on thecollecting.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed at any point on apattern field of the e-beam column that includes the underlyingpatterned feature.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed at a plurality oflocations within a single die location, the plurality of locationscorresponding to a plurality of underlying alignment marks of theunderlying patterned feature.

In one embodiment, the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed on the order ofhundreds of times within a single die location.

In one embodiment, time positions of an e-beam of the e-beam column areregistered against the plurality of underlying alignment marks of theunderlying patterned feature during scanning of the stage using drop incells.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes fitting polynomials.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes estimating complexcorrection parameters of higher orders.

In one embodiment, performing the corrections of the alignment of thestage relative to the e-beam column excludes fitting polynomials andexcludes estimating complex correction parameters of higher orders.

What is claimed is:
 1. A method of real-time alignment of a wafersituated on a stage of an e-beam tool, the method comprising: collectingbackscattered electrons from an underlying patterned feature of thewafer while an e-beam column of the e-beam tool writes during scanningof the stage, the collecting performed by an electron detector placed atthe e-beam column bottom; and performing corrections of an alignment ofthe stage relative to the e-beam column based on the collecting.
 2. Themethod of claim 1, wherein the collecting the backscattered electronsfrom the underlying patterned feature of the wafer is performed at anypoint on a pattern field of the e-beam column comprising the underlyingpatterned feature.
 3. The method of claim 2, wherein the collecting thebackscattered electrons from the underlying patterned feature of thewafer is performed at a plurality of locations within a single dielocation, the plurality of locations corresponding to a plurality ofunderlying alignment marks of the underlying patterned feature.
 4. Themethod of claim 3, wherein the collecting the backscattered electronsfrom the underlying patterned feature of the wafer is performed on theorder of hundreds of times within a single die location.
 5. The methodof claim 3, wherein time positions of an e-beam of the e-beam column areregistered against the plurality of underlying alignment marks of theunderlying patterned feature during scanning of the stage using drop incells.
 6. The method of claim 1, wherein performing the corrections ofthe alignment of the stage relative to the e-beam column excludesfitting polynomials.
 7. The method of claim 1, wherein performing thecorrections of the alignment of the stage relative to the e-beam columnexcludes estimating complex correction parameters of higher orders. 8.The method of claim 1, wherein performing the corrections of thealignment of the stage relative to the e-beam column excludes fittingpolynomials and excludes estimating complex correction parameters ofhigher orders.
 9. A column for e-beam tool, the column comprising: anelectron source for providing a beam of electrons; a limiting aperturecoupled with the electron source along a pathway of the beam of the beamof electrons; high aspect ratio illumination optics coupled with thelimiting aperture along the pathway of the beam of the beam ofelectrons; a shaping aperture coupled with the high aspect ratioillumination optics along the pathway of the beam of the beam ofelectrons; a blanker aperture array (BAA) coupled with the shapingaperture along the pathway of the beam of the beam of electrons; a finalaperture coupled with the BAA along the pathway of the beam of the beamof electrons; a sample stage for receiving the beam of electrons; and anelectron detector for collecting backscattered electrons from anunderlying patterned feature of a sample wafer on the sample stage whilescanning the sample stage in a scan direction during an e-beam columnwriting operation, the e-beam column writing operation using the beam ofelectrons.
 10. The column of claim 9, wherein the BAA is a three beamstaggered blanker aperture array.
 11. The column of claim 9, wherein theBAA is a universal cutter blanker aperture array.
 12. The column ofclaim 9, wherein the BAA is a non-universal cutter blanker aperturearray.
 13. A non-transitory machine-accessible storage medium havinginstructions stored thereon which cause a data processing system toperform a method of real-time alignment of a wafer situated on a stageof an e-beam tool, the method comprising: collecting backscatteredelectrons from an underlying patterned feature of the wafer while ane-beam column of the e-beam tool writes during scanning of the stage,the collecting performed by an electron detector placed at the e-beamcolumn bottom; and performing corrections of an alignment of the stagerelative to the e-beam column based on the collecting.
 14. The storagemedium as in claim 13, wherein the collecting the backscatteredelectrons from the underlying patterned feature of the wafer isperformed at any point on a pattern field of the e-beam columncomprising the underlying patterned feature.
 15. The storage medium asin claim 14, wherein the collecting the backscattered electrons from theunderlying patterned feature of the wafer is performed at a plurality oflocations within a single die location, the plurality of locationscorresponding to a plurality of underlying alignment marks of theunderlying patterned feature.
 16. The storage medium as in claim 15,wherein the collecting the backscattered electrons from the underlyingpatterned feature of the wafer is performed on the order of hundreds oftimes within a single die location.
 17. The storage medium as in claim15, wherein time positions of an e-beam of the e-beam column areregistered against the plurality of underlying alignment marks of theunderlying patterned feature during scanning of the stage using drop incells.
 18. The storage medium as in claim 13, wherein performing thecorrections of the alignment of the stage relative to the e-beam columnexcludes fitting polynomials.
 19. The storage medium as in claim 13,wherein performing the corrections of the alignment of the stagerelative to the e-beam column excludes estimating complex correctionparameters of higher orders.
 20. The storage medium as in claim 13,wherein performing the corrections of the alignment of the stagerelative to the e-beam column excludes fitting polynomials and excludesestimating complex correction parameters of higher orders.